<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>移动端</title>
  <style>
    html {
      font-size: 10px;
    }

    .box {
      font-size: 1.4rem;
    }

    a {
      font-size: 1.3rem;
    }
  </style>
</head>

<body>

  <div class="box">今天气温30度</div>
  <a href="#00">百度</a>
</body>

</html>